Environment

AEM 6.x

Cause

1. One possible cause is that the bundle has no exports or imports or any code in it. This is known to cause the issue.
2. The custom bundle could be exporting system level java packages that are already exported and used by some core AEM, Apache Felix or Sling bundle

Resolution

Empty OSGi Bundle

If you are deploying an empty bundle then stop doing so. It is not valid to do so unless it is a fragment bundle containing resources.

System Level Export

If you are exporting some library that is used by the system (AEM, Sling, Apache Felix, Oak, etc.), then modify your custom bundle to embed the library using the maven-bundle-plugin <Embed-Dependency> tag. You can choose whether or not to add the library to the <Export-Package> tag. You will still be able to access the library within the code in the bundle but it wouldn't be exported to all other bundles.